This invention relates to bumper end cap assemblies for carriers used in pneumatic tube systems.
Pneumatic tube systems using carriers for dispatching mail, transmission of cash and other relatively small items have been used for many decades. In recent times, such systems' inherent characteristics have caused their adoption by financial organizations such as banks and savings institutions having consumer drive-in facilities. Typically, a consumer at an external end station to the system will put deposit slips and cash or checks, etc into a carrier to be transmitted to an internal station which processes the contents and returns a receipt.
The nature of this usage necessarily exposes the individual carriers to a wide variety of ambient conditions and degrees of abuse. Further, the tube systems per se are rarely "straight line" and thus the carriers have to traverse bends of various degrees of severity. The systems also are often designed with control levers which are engaged by the carriers in passage.
For consumer and institutional acceptability the carriers must be ruggedly constructed, esthetically pleasing and able to function with a high speed of passage from end station to end station. The higher the speed of passage, the greater the shock forces the carrier must encounter in stopping at the end stations. Carrier bumper end caps are used to absorb the shocks.
For many decades the most common type of end cap and bumper for the carriers has been a compressed felt end cap which is fastened to the outboard ends of the carrier and traps the disc like air skirt between the bumper and the end of the carrier body. Examples of various configurations are shown in prior art U.S. Pat. Nos. 1,476,070; 1,779,164; and 2,053,671. However compressed felt bumpers inherently have disadvantages. Among these are the presenting of relatively high frictional qualities when the bumper engages a tube wall during a bend, being by nature subject to some absorption of water from the atmosphere or from contact, and not well adopted for good wear characteristics or good appearance when in use because of handling and engaging control levers in the tube systems. The variability of ambient conditions and degradation of the end caps caused by consumer handling of carriers at the exterior stations exacerbate the inherent negative characteristics of the felt bumpers.
Attempts at providing bumper end caps for carriers which are made of materials other than felt have been tried. These have suffered one or more of the following disabilities: excessive number of parts; greatly increasing the overall length of the carrier as a percent of useful carrier space; hard to attach and detach; hard to keep clean; hard to assemble to the carrier; and esthetically unattractive after handling and use. Some examples are shown in U.S. Pat. Nos. 760,701 and 3,187,886.
The bumper end cap assembly here disclosed overcomes the prior art deficiencies. A hard moldable plastic wheel-like wear surface member interfits with a relatively softer moldable plastic shock absorbing member to simultaneously provide good wear and shock absorbing characteristics during tube transit and at end stations. The shock absorbing member underlays the wheel-like member and takes up shocks during transit or during accidental misuse by consumer handling, and is formed to extend axially beyond the wheel-like member in the aperatures of the spokes thereof and thereby take up the shock directly at the end stations. The wheel-like member provides precision rapid attachment-detachment surfaces. The entire assembly is well adapted for its intended purposes, is long wearing, is esthetically pleasing during use and handling, is easy to assemble and disassemble by non-skilled labor, is easy to store and pack, is well adapted for color coding, can be manufactured with repeatable precision, is rugged, is well adapted for mass manufacturing techniques, is easy to maintain and be kept clean and is of high quality.